Cutter-head structure

ABSTRACT

A CUTTER HEAD WITH A CHIPPING TOOTH FOR TAKING SLICES OF WOOD FROM A WORK PIECE, THE SLICES SEPARATING INTO CARDS BY HORIZONTAL SHEAR, AND INCORPORATING A SPLITTER WHICH INITIATES ON THE CARDS AS THEY ARE PROJECTED FROM THE CUTTING TOOTH A VERTICAL SHEAR TO INSURE THAT THE CARDS WILL BE DIVIDED INTO CHIPS OF A WIDTH MOST DESIRABLE FOR THE DIGESTING PROCESS OF A HIGH-GRADE PULPING OPERATION.

June 5, 1973 CHAPMAN ETAL Re. 27,654

CUTTER-HEAD STRUCTURE Original Filed Aug. 16. 1967 United States Patent27,654 CUTTER-HEAD STRUCTURE Frederic F. Chapman, Coquitlam, BritishColumbia, and

Daniel Hill, Kelowna, British Columbia, Canada, assignors to Ernest E.Runnion, Shelton, Wash.

Original No. 3,487,865, dated Jan. 6, 1970, Ser. No. 661,062, Aug. 16,1967. Application for reissue May 17, 1971, Ser. No. 144,159

Int. Cl. B27g 13/00 U.S. Cl. 144229 16 Claims Matter enclosed in heavybrackets appears in the original patent but forms no part of thisreissue specification; matter printed in italics indicates the additionsmade by reissue.

ABSTRACT OF THE DISCLOSURE A cutter head with a chipping tooth fortaking slices of wood from a work piece, the slices separating intocards by horizontal shear, and incorporating a splitter which initiateson the cards as they are projected from the cutting tooth a verticalshear to insure that the cards will be divided into chips of a Widthmost desirable for the digesting process of a high-grade pulpingoperation.

This invention relates to cutter heads for use in producing pulp chips.Rotary cutter heads designed for this purpose are customarily comprisedof a plurality of head sections mounted in side-by-side relation upon arotary arbor, with each head carrying at least one chipping tooth whichin each revolution of the cutter head bites into a work piece and cuts aslice of wood therefrom. A highly desirable width for the chipping teethis between two and three inches. The slice which comes off the workpiece separates into what are commonly termed cards by the force ofshearing fractures which take place along the grain in generallyparallel planes more or less tangent to circles having the rotary axisof the cutter head as a center. This separation force is generallyreferred to as a horizontal shear in distinguishing the same from othershearing fractures, commonly known as vertical shear, which act alongthe grain of the cards in planes at right angles to the horizontal shearand cause the cards to break into two or more pieces of narnower width.An ideal chip is one having a width no narrower than /2" nor wider than1 but where natural vertical shear is relied upon it develops that afair portion of the chips are either under-size or over-size. Thepresent invention proposes as its principal object to provide achip-cutting cutter head having in association with its chipping tooth asplitter functional to initiate in the cards as they are projected fromthe tooth, at a predetermined point in the width thereof, the verticalshear responsible for breaking the cards into chips.

With the above object in view and further aiming to provide an otherwiseadvanced cutter head, the invention consists in the novel constructionand in the adaptation and combination of parts hereinafter described andclaimed.

In the accompanying drawing:

FIGURE 1 is a transverse vertical sectional view showing two of theplural head sections of a cutter head constructed to embody preferredteachings of the present invention, one of said two head sections beingshown in full lines and the other in broken lines.

FIG. 2 is a fragmentary side elevational view thereof.

FIG. 3 is an exploded perspective view portraying a chipping tooth.splitter, and clamping block removed from the cutter head.

FIG. 4 is a fragmentary transverse vertical sectional view drawn to anenlarged scale on line 4-4 of FIG. 2; and

"ice

FIG. 5 is a fragmentary sectional view on line 55 of FIG. 4.

Description of invention Cutter heads of the type to which the presentinvention is directed, intended for use in producing pulp chips,customarily have a set of several head sections with each sectioncarrying a single chipping knife. The head sections are keyed orotherwise securely attached upon a power-driven rotary arbor, so as tolie in side-by-side relation with the several knives in the set locatedat equidistantly spaced intervals, say 22Vi, of a circle having therotary axis of the arbor as its center. Two of the head sections areshown in the drawing and denoted by the numeral 10. Knives carriedthereby are designated by 11, and the rotary arbor by 12.

According to the present invention each head section has two radial armswhich lie diametrically opposite one another, one arm 13 serving as abalancing arm and the other arm 14 presenting a socket for the mountingof the knife. The socket is open-sided and has an angular profileconfiguration to provide two planar walls 15 and 16 which respectivelyserve as a back wall and an inner end wall for the socket. The back wallis biased, say 20 or so, forwardly from a plane projected radial to thehead through the juncture of the two walls. The inner end wall 16extends forwardly from the back wall in a plane normal thereto.

Forwardly beyond the frontal limit of said end wall 16 the mounting armis notched to provide two meeting flats 17 and 18. Fiat 17 is located inobtuse angular relation, say to the end wall. Flat 18 desirably liesparallel to the end wall. A bolt-hole 19 is drilled through the mountingarm with its axis placed normal to the fiat 17 and centered relativethereto. Accommodated by the bolt-hole is a cap-screw 20 which threadsinto a clamping block 21, drawing the block downwardly upon thehereinafter-described knife to secure the latter in the socket.

The knife-clamp 21 has the shape of an irregular right hexagonal prism,which is to say a figure with six rectangular faces. Only three of thefaces, denoted by 22, 23 and 24, have functional significance. Face 22fits against the flat 18. It bears to the face 23 the same angularrelationship which exists between the flats 18 and 17. Face 24 is biasedsomewhat less than is the face 22 from the plane in which theintervening face 23 lies, say 30 as compared with 50. The clamping blocktakes its purchase by the engagement of the face 22 against the flat 18.The clamping office is performed by the face 24, which lies in acuteangular relation to the end wall of the socket and bears against a frontface 25 presented by a root section 26 of the knife. The root sectionhas a planar back face which seats upon the back wall 15 of the socketand an inner end face disposed normal thereto. The front face 25 lies inacute angular relation to the end face. A facing 27 of babbitt-metaloverlies the end face and is adapted to seat against the end wall 16 ofthe socket. The root section has planar side faces disposed normal tothe back face and the width corresponds to the width of the hubs 28 ofthe cutter-head sections. When a set of knife-carrying cutter-headsections are mounted upon the arbor, the arrangement is one in which theroot sections of the knives have their leading edge moderately lappingthe following edge of a preceding root section.

Said babbitt facing 27 compensates the knife to sharpening operationsperformed upon a forwardly hooked chipping tooth 30 which projectsradially from the root section, serving to maintain a constant cuttingradius and angle of attack throughout the usuable life of the knife. Inthe pouring of the babbitt-metal, the same is locked to the root sectionby flowing into a pocket 31 which is exposed to the inner end face 32 ofthe root section, extending the full length of such face on the medianline thereof.

The root section presents in its upper portion a parallel-sicled groove33 exposed to the front face 25 and extending on the longitudinal medianline of the root section from the babbitt pocket 31 to a throat 34 cutback rather deeply from the chipping tooth 30. The front face 25 definesa plane intersecting the projecting extremity between the cutting edge30 and the concave surface 35. The parallel walls defining the groove 33or planar slot are formed in the metal body 29. The planar slot adjacentthe throat 34 cooperates with the throat to de ine a bladereceivingspace extending to the concave surface 35. A hardened metal blade 36fits in said groove with its inner end projecting into the pocket 31 soas to be invested by the poured babbitt. The outer end projects as atongue into the throat and has its forwardly facing edge bevelled, as at37. Such bevelled edge performs a splitting function upon wood cards cutby the tooth. The slope given to the bevelled surfaces is quite shallowin that it is not intended that the splitting tongue cut into the card.Rather, it is to initiate a line fracture upon an end edge of the cardsas the cards are propelled from the tooth 30 into the throat 34. Thisinsures that a bisecting vertical shear will t occur, dividing each cardinto two chips. It will be understood that the cards are themselves aproduct of shearing stress, in this instance horizontal, as thesuccessive slices cut by the knife from a work piece divide themselvesinto a plurality of cards.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Means for producing pulp chips comprising a cutter head mounted forrotation on a power driven arbor, a chipper tooth having a cutting edgemounted on said cutter head, means for securing the chipper tooth to thecutter head so that the cutting edge of the chipper tooth extends beyondthe periphery of the cutter head, the cutting edge of said cutting toothbeing parallel to the axis of rotation of said cutter head, a chipsplitting means carried by the cutter tooth at a right angle to saidcutting edge for splitting a severed pulp chip into a plurality of chipsand said chip splitting means positioned on said chipper tooth inwardlyand rcarwardly from the cutting edge and intermediate the sides of saidcutting tooth.

2. Structure according to claim 1 in which the chipping knife has a rootsection which is clamped in a mating socket provided by the cutter head,the tooth projecting radially outwardly from the root section with itscutting edge overhanging a throat through which the chips are projected,the splitting means comprising a bevel-edged tongue which extends intothe throat of the tooth from a base part of the chipping tooth.

3. Structure according to claim 2 having a means common to both thechipper tooth and the tongue performing a keeper function for the latterand the clamping function for the root section of the former.

4. Structure according to claim 2 in which the root section provides agroove in which the base part of the splitting means is fitted, thekeeping of said base part in the groove and the clamping of the rootsection in its socket being performed by a block tensioned against theroot section by a cap screw received through a bolt-hole which extendsin offset relation to the rotary axis of the cutter head between twoflats which are formed in the perimeter of the cutter head at oppositesides thereof.

5. For the production of pulp chips, a rotary cutter head providing aradial arm formed in its leading side with a socket which provides aback wall and an inner wall and has the flanking sides open, andforwardly beyond the inner wall presents a notch which is made angularto provide a back wall and an inner wall, a chipping tooth having a rootsection which seats in the socket and a tooth section which extendsoutwardly and forwardly from the root section, the root sectionproviding front, back and inner faces, the back and inner facesrespectively bearing against the back and inner walls of the socket andthe front face converging in an outward direction toward the back face,a clamping block bearing by one face against the inner wall of the notchand by another face against the front face of said root section of theknife, the radial arm having a through bolt-hole extending back-to-frontto said back wall of the notch from a flat formed upon the trailing sideof the arm, and a cap screw received through the bolt-hole taking a headpurchase upon said flat and threading into the clamping block fordrawing the block against said front face of the chipping tooths rootsection, a splitter carried by the chipping tooth to occupy aninterruptive position in the path of a chip projected from the tooth andby said interruption performing a splitting influence to promote a chip,a vertical shear dividing a chip along the grain of the wood into atleast two chips, the splitter comprising a blade fitting in a grooveprovided in the knifes root section on the median longitudinal verticalplane thereof.

6. For the production of pulp chips using a rotary cutter head, achipping knife comprising a metal body having a root section formounting on the rotary cutter head and a hookea. chipping toothprojecting outwardly from the root section, the hooked chipping toothhaving a cutting edge formed on the projecting extremity thereof and aconcavely curved throat at the juncture with root section, a centralslot formed in said root section adjacent said throat and substantiallyperpendicular to said cutting edge, a chip splitting blade mounted insaid slot and extending into said throat, said blade having a splittingedge facing and spaced a substantial distance from said cutting edge forsplitting the severed pulp chips.

7. The chipping knife of claim 6 wherein the hooked chipping tooth is ofa generally tapered cross-section thickening toward the root section.

8. The chipping knife of claim 6 wherein said root section has a pocketformed adjacent said slot, said splitter blade extends into said pocket,and babbitt metal filling said pocket for supporting and securing saidblade.

9. The chipping knife of claim 6 wherein said splitting edge comprisesshallowly bevelled surfaces facing in both lateral directions forfracturing the severed chip and urging the two resultant chips laterallyfor assisting in discharging the chips from the knife throat.

10. For use with a rotary cutter head and a chip splitting blade, theimprovement comprising: a chipping knife for the production of pulpchips, said chipping knife having a metal body provided with a rootsection for detachable mounting on the rotary cutter head, the rootsection having a front face, a rear face, and an inner end faceextending therebetween, said rear face and inner end face each beingshaped for solid surface contact with the rotary cutter head, said metalbody having a hooked chipping tooth projecting outwardly from said rootsection and hooking in the direction of rotation of the rotary cutterhead, said hooked chipping tooth having a projecting extremity with acutting edge facing the direction of rotation, said hooked chippingtooth also having a concave surface extending rearward of said frontface and forming a throat facing the direction of rotation fordischarging chips severed by said cutting edge, said front face defininga plane intersecting said projecting extremity between said cutting edgeand said concave surface, and walls forming a planar slot in said bodyand said front face and cooperating with said throat to define ablade-receiving space, said slot being substantially perpendicular tosaid cutting edge to receive a blade for laterally splitting severedchips entering the throat.

I]. The chipping knife of claim 10 wherein said root section has apocket formed adjacent said slot for receiving and retaining babbittmetal to secured and support the splitting blade.

12 A chipping knife for mourning on a rotary cutter head, comprising, anintegral metal body having a generally rectangular root section formounting on the cutter head and a hook-shaped chipping tooth of anirregular tapering cross-section extending outwardly from said rootsection, said chipping tooth tapering to a cutting edge at its outwardextremity, said chipping tooth having an inner surface elxtending fromsaid cutting edge to said root section and forming a curved throat intowhich the chips proceed upon severing by said cutting edge, and acentrally located splitter means positioned in said throat and having asplitting edge perpendicular to and spaced from said cutting edge tolaterally divide a severed chip into two chips.

13. A chipping knife for mounting on a rotary cutter head, comprising, aroot section for mounting the knife on the cutter head and chippingtooth projecting outwardly from said root section, said chipping toothhaving a cutoing edge at its outward extremity, and a splitter meanshaving a splitting edge generally perpendicular to and spaced rearwardlyfrom said cutting edge to laterally fracture a severed chip into twochips.

14. The chipping knife of claim 13 wherein said splitting meanscomprises a separate flat blade having said splitting edge.

15. The chipping knife of claim 13 wherein said splitting edge is spaceda suflicient distance from said cutting edge for the chip to have beensubstantially completely severed from the wood by the cutting edge forthe splitting edge to readily fracture the severed chip.

16. The chipping knife of claim 15 wherein said chipping tooth has asurface between said cutting edge and splitting edge for engaging thecut surface of the chips and wedging the severed chips toward thesplitting edge.

References Cited The following references, cited by the Examiner, are

of record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 3,017,912 1/1962 Sybertz 144-326 A 709,526 9/ 1902Taylor 144-230 2,449,605 9/1948 Kelton 144-230 2,784,753 3/1957 Kleim etal. 144-172 X 2,899,992 8/ 1959 Key 144-218 X 3,237,275 3/1966 Middleton144-229 X FOREIGN PATENTS 254,871 1/1949 Switzerland 144-230 GILWEIDENFELD, Primary Examiner US. Cl. X.R.

